Electronic apparatus having security function

ABSTRACT

When an electronic apparatus is forcibly put into an inoperable state by theft, the inoperable state is canceled using a code from a dealer, without carrying the electronic apparatus into the dealer. After electric power is supplied again, a CD reproduction apparatus is used to playback a CD, and TOC information is used as a code C 1 . When code C 1  is identical to an authorized code A 21,  the electronic apparatus is made operable. To cancel the inoperable state after the number of inconsistencies becomes 10 or more, a code A 22  is notified to the dealer. The dealer carries out a calculation using the code A 22,  and a result B 2  of the calculation is notified to the user. An individual code calculating means carries out the same calculation as the above-mentioned calculation and obtains calculation result B 3.  When calculation result B 2  coincides with calculation result B 3,  the inoperable state is canceled.

This application is a continuation of U.S. application Ser. No.11/192,016, filed Jul. 29, 2005, now abandoned, which is a divisional ofU.S. application Ser. No. 09/360,142, filed Jul. 26, 1999, now U.S. Pat.No. 7,093,300.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electronic apparatus having asecurity function for theft prevention.

2. Description of the Related Art

Examples of this kind of electronic apparatus are audio apparatuses,such as a compact disc reproduction apparatus, a radio receiver, amagnetic tape reproduction apparatus and a television set, mounted onvehicles, such as cars. This kind of electronic apparatus mounted on avehicle is in danger of being removed from the vehicle and stolen. Toprevent theft, a conventional electronic apparatus is configured suchthat when the electronic apparatus is reconnected to its power source,such as a battery, a predetermined identification code (abbreviated asID) is required to be input. Only when the input identification code isthe predetermined authorized code, the intrinsic operation of theelectronic apparatus is carried out. When the authorized identificationcode is not input, the intrinsic operation of the electronic apparatuscannot be carried out.

Furthermore, to ensure this theft prevention, the number of times otherwrong identification codes are input repeatedly while the authorizedidentification code is not input is counted by a counter. When the countvalue reaches a predetermined value or more, the electronic apparatusenters a dealer carry-in mode. In order to cancel the dealer carry-inmode so that the electronic apparatus can carry out its intrinsicoperation, the electronic apparatus must be carried in to the dealer,where a master code must be input in the electronic apparatus. Themaster code has been determined commonly to every product of theelectronic apparatus. For this reason, this master code is not disclosedto users, but strictly retained by the dealer. The dealer is herein astore or workshop for such electronic apparatuses, or for cars on whichsuch electronic apparatuses are mounted.

The facts that the identification code is necessary to make this kind ofelectronic apparatus carry out its intrinsic operation, and that themaster code is necessary in the dealer carry-in mode of the electronicapparatus should be known widely and generally by advertisement, wherebythe electronic apparatus is not targeted for theft, and can be preventedfrom being stolen.

In the above-mentioned prior art, when the number of times unauthorizedidentification codes are input by the user reaches a predetermined valueor more, the electronic apparatus enters the dealer carry-in mode, inspite of no theft. In the case of a configuration wherein the userinputs the identification code by using numeric keys, for example, theuser may forget the identification code, whereby the apparatus entersthe dealer carry-in mode. In the case of a configuration wherein a partof the content recorded on a compact disc to be read by the compact discreproduction apparatus of the user is used as the identification code,when the compact disc of the user is damaged or lost, or when a wrongcompact disc is played back a plurality of times, the apparatus entersthe dealer carry-in mode. In these prior arts, the apparatus havingentered the dealer carry-in mode as described above must be carried inthe dealer.

In the prior arts, therefore, the electronic apparatus having enteredthe dealer carry-in mode must be carried in the dealer by the user.Furthermore, the dealer must cancel the dealer carry-in mode so that theelectronic apparatus can perform its intrinsic operation. As a result,much effort and cost are required to cancel the dealer carry-in mode ofthe electronic apparatus in the case of the prior arts.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an electronic apparatushaving a security function, wherein, when the electronic apparatus fallsinto an inoperable state and cannot perform its intrinsic operation toattain security and prevent theft, the inoperable state can be canceledrelatively easily.

Another object of the present invention is to provide a method ofcanceling the inoperable state of an electronic apparatus having asecurity function wherein the inoperable state of the electronicapparatus, caused to prevent theft, can be canceled at minimal effortand cost.

A still another object of the present invention is to provide adealer-use calculation device for an electronic apparatus having asecurity function, wherein the inoperable state of the electronicapparatus, caused to prevent theft, can be canceled at minimal effortand cost.

The present invention provides an electronic apparatus having a securityfunction, comprising: theft judging means for judging that theelectronic apparatus has been exposed to theft; inoperable state settingmeans, in response to an output of the theft judging means, for, whenthe apparatus is judged as having been exposed to theft, putting theelectronic apparatus into an inoperable state against theft in which apredetermined operation of a controlled circuit is disabled; anonvolatile individual code memory M22 for storing an individual codeA22 individually assigned to the electronic apparatus; output means foroutputting an output code A221 having a predetermined first relationshipwith the individual code A22; input means for inputting an individualjudgment code B2; individual code relationship judging means for judgingwhether the individual judgment code B2 input by the input means and theindividual code A22 have a predetermined second relationship; andinoperable state canceling means for, when it is judged by theindividual code relationship judging means that the individual judgmentcode B2 and the individual code A22 have the predetermined secondrelationship, canceling the inoperable state against theft of thecontrolled circuit.

Further, in the present invention, the electronic apparatus having asecurity function is characterized in that when the output code A221 andthe individual judgment code B2 have a predetermined third relationship,the individual judgment code B2 and the individual code A22 have thepredetermined second relationship.

According to the present invention, the electronic apparatus having asecurity function is mounted on a vehicle such as a car, and may be anaudio apparatus such as a compact disc reproduction apparatus, a radioreceiver, a magnetic tape reproduction apparatus or a television set, ormay be another kind of electronic apparatus. The theft judging meansjudges that the electronic apparatus has been exposed to theft or anequivalent, and forcibly puts the controlled circuit of the electronicapparatus into the inoperable state against theft, that is, a secondinoperable state which will be described later.

To cancel such an inoperable state against theft of the controlledcircuit of the electronic apparatus, the individual code A22individually assigned to the electronic apparatus and stored in theindividual code memory M22 is used. The individual code A22 iscalculated in accordance with a predetermined first relationship, sothat the output code A221 is obtained. With regard to this firstrelationship: (a) the value of the output code A221 may be the same asthat of the individual code A22; (b) the individual code A22 may besubjected to calculation in accordance with a predetermined equation toobtain an output code A221 having a different value from that of theindividual code A22; or (c) an output code A221 having a different valuefrom that of the individual code A22 may be obtained in accordance witha preset table or the like. The output code A221 obtained in this way isoutput from the output means embodied by indication means or the like.

The output code A221 output from the output means is subjected tocalculation in accordance with a predetermined third relationship, andthe individual judgment code B2 is obtained from the calculation result.Such an output code A221 in accordance with the third relationship isobtained by calculation by a dealer-use calculation device provided forthe dealer, for example.

The individual judgment code B2 is supplied to the individual coderelationship judging means by the input means. The individual coderelationship judging means judges whether the individual code A22 storedin the individual code memory M22 has a predetermined secondrelationship with the individual judgment code B2 input by the inputmeans. The inoperable state canceling means cancels the inoperable stateagainst theft of the controlled circuit of the electronic apparatus whenthe individual judgment code B2 and the individual code A22 have thesecond relationship. As a result, the electronic apparatus can carry outits usual intrinsic operation.

When the output code A221 having a first relationship with theindividual code A22 have a third relationship with the individualjudgment code B2, the individual judgment code B2 and the individualcode A22 have a second relationship. As shown above, the first to thirdrelationships are related to each other.

Furthermore, the present invention provides an electronic apparatushaving a security function, comprising theft judging means for judgingthe electronic apparatus as having been exposed to theft or anequivalent; inoperable state setting means, in response to an output ofthe theft judging means for, when the apparatus is judged as having beenexposed to theft, putting the electronic apparatus into an inoperablestate in which a predetermined operation of a controlled circuit isdisabled; a nonvolatile individual code memory M22 for storing anindividual code A22 individually assigned to the electronic apparatus;indication means for reading the individual code A22 from the individualcode memory M22 and indicating the code A22; input means for inputtingan individual judgment code B2; individual code calculating means forcarrying out predetermined individual code calculation by using theindividual code A22; individual code relationship judging means forjudging whether an individual judgment code B2 and a code B3 indicatingthe calculation result from the individual code calculating means have apredetermined individual judgment relationship; and inoperable statecanceling means, in response to an output of the individual coderelationship judging means, for canceling an inoperable state when it isjudged that the individual judgment code B2 and the code B3 indicatingthe calculation result from the individual code calculating means havethe individual judgment relationship.

According to the present invention, the same as in the case of thecondition judgment means, in the case where the theft judging meansjudges that the electronic apparatus has been exposed to theft or anequivalent to theft, the controlled circuit included in the electronicapparatus is forcibly put into an inoperable state similar to theabove-mentioned second inoperable state. This inoperable state iscanceled just as described above when it is judged by the individualcode relationship judging means that the code B3 obtained by thecalculation of the individual code calculating means by using theindividual code A22 individually assigned to each product of theelectronic apparatus and the individual judgment code B2 notified by thedealer to the user and input through the individual judgment code inputmeans by the user have the predetermined individual judgmentrelationship, for example, when they are identical to each other.

The individual code A22 stored in the individual code memory M22 isindicated by the indication means. The individual code A22 indicated bythe indication means is notified by the user to the dealer. The dealercarries out calculation similar to the predetermined individual codecalculation carried out by the above-mentioned individual codecalculating means, by using the individual code A22 notified by theuser, and the calculation result B3 is then notified to the user. Theuser inputs the code B3 notified from the dealer, as the individualjudgment code B2.

The indication means may be a visual indication means embodied by liquidcrystal, a cathode ray tube or the like, or may be formed so as to carryout audio notification by outputting a voice signal generated by a voicesynthesis circuit.

According to the present invention, as in a case where the electronicapparatus is stolen, when the electronic apparatus is removed from avehicle with electric power being shut off from its power source such asa battery of the vehicle such as a car, the electronic apparatus isremoved from the vehicle, the power source is connected again to supplyelectric power, and the authorized judgment identification code C1 isnot input, the electronic apparatus is forcibly set to an inoperablestate similar to the above-mentioned second inoperable state, wherebythe security function is attained. The individual code A22 indicated bythe indication means is notified by the user to the dealer, for example.The individual judgment code B2 obtained from the dealer is input by theuser through the input operation of the individual judgment code inputmeans. When the individual judgment code B2 input as described above andthe code B3 obtained by calculation by using the individual code A22stored in the individual code memory M22 of the electronic apparatushave the individual judgment relationship, for example, when they areidentical to each other, the inoperable state of the electronicapparatus is canceled. Therefore, it is not necessary for the user tocarry the electronic apparatus in the dealer to cancel the inoperablestate of the electronic apparatus.

Furthermore, in the present invention, the indication means furtherindicates the intrinsic operation state of the controlled circuit, andthe intrinsic operation of the controlled circuit is controlled by theoutput of the input means.

According to the present invention, the indication means and the inputmeans are used for the intrinsic operation of the controlled circuit ofthe electronic apparatus. The indication means and the input means arealso used to attain the security function for canceling the inoperablestate. Therefore, it is not necessary to additionally provide anyindication means and input means to ensure security for the electronicapparatus, whereby the configuration of the apparatus can be simplified.As a result, the electronic apparatus can be made compact according tothe present invention. This is particularly important when theelectronic apparatus is embodied in relation to an audio apparatusmounted on a vehicle, such as a car.

Furthermore, in the present invention, the electronic apparatus having asecurity function is characterized in that the individual code A22 is aproduction number A12 of the electronic apparatus.

Furthermore, in the present invention, the electronic apparatus having asecurity function further comprises: a nonvolatile unique memory M12 forstoring data A12 unique to the electronic apparatus; and calculatingmeans for carrying out a predetermined calculation by using the uniquedata A12 stored in the unique memory M12, and storing the calculationresult B1 in the individual code memory M22 as the individual code A22.

According to the present invention, the individual code A22 stored inthe individual code memory M22 may be the production number A12 of theelectronic apparatus itself. On the other hand, in the case of anotherembodiment of the present invention, a predetermined calculation asshown in FIG. 12, mentioned later, may be carried out by using theproduction number A12 stored in the production number memory M12 tostore the calculation result in the individual code memory M22 as theindividual code A22.

Furthermore, in the present invention, the electronic apparatus having asecurity function is characterized in that the data A12 unique to theelectronic apparatus is the production number.

According to the present invention, to calculate the individual code A22to be stored in the individual code memory M22, the data A12 and A13unique to the electronic apparatus are used. The data unique to theelectronic apparatus may be, for example: (a) the above-mentionedproduction number A12 itself; (b) a fixed value A13 unique to theelectronic apparatus previously stored in a memory area M13, asmentioned later, which is a value other than the production number; (c)both the production number A12 and the fixed value A13 as shown in FIG.13, mentioned later; or (d) another data unique to the electronicapparatus.

Furthermore, the present invention further comprises: a nonvolatileproduction number memory M12 for storing the production number A12 ofthe electronic apparatus; and a production number calculating means forcarrying out predetermined production number calculation by using theproduction number A12 stored in the production number memory M12, andfor storing the calculation result B1 as the individual code A22 in theindividual code memory M22.

According to the present invention, the electronic apparatus is providedwith the production number memory M12 to determine an individual codeA22 unique to each product of the electronic apparatus. The serialproduction number A12 of each product of the electronic apparatus isstored in the memory M12. The production number calculating meanscarries out the predetermined production number calculation by using theproduction number A12 stored in the production number memory M12. Thecalculation result Bi is used as the individual code A22.

According to the present invention, the production number A12 isobtained as the calculation result B1 by the predetermined productionnumber calculation, and the calculation result B1 is used as theindividual code A22. The production number A12 is thus not directly usedas the individual code A22. This prevents the production number printedon the nameplate of the electronic apparatus, for example, from beingdirectly used as the production number A12 for the predeterminedindividual code calculation by the thief. In addition, the individualcode A22 can easily be assigned individually to the electronicapparatus.

According to the present invention, the individual code A22 assignedindividually to each product of the electronic apparatus is obtained bycarrying out the predetermined production number calculation by usingthe production number A12 of the electronic apparatus. Therefore, theindividual code A22 can be set to a value unique to each product.Instead of directly using the production number A12 as the individualcode A22, the production number A12 is subjected to the calculation toobtain the individual code A22. This configuration is thus moreeffective in theft prevention than the configuration wherein theproduction number A12 is directly used as the individual code A22. Thepredetermined production number calculation for obtaining the individualcode A22 from the production number A12 can be attained by theproduction number calculating means embodied by a microcomputer.Therefore, it is not necessary to manually prepare a comparison tablefor the production number and the individual code A22, and it ispossible to save effort for storing the comparison table in anonvolatile memory. By storing the production number A12 in thenonvolatile production number memory M12, the individual code A22 can beobtained automatically by the calculation, whereby effort and cost canbe reduced.

Furthermore, in the present invention, in response to the input of theindividual judgment code B2 by the input means, the individual code A22is updated by a predetermined calculation.

Furthermore, in the present invention, the individual code memory M22 isa writable memory, and the electronic apparatus further compriseswriting means. The writing means, in response to the output of theindividual code relationship judging means, when it is judged that theindividual judgment code B2 from the individual judgment code inputmeans and the code B3 for indicating the calculation result from theindividual code calculating means have the predetermined individualjudgment relationship, writes and updates the individual judgment codeB2 from the individual judgment code input means or the calculationresult B3 of the individual calculating means in the individual codememory M22 as a new individual code for the next calculation of theindividual code calculating means.

According to the present invention, the individual judgment code B2 fromthe individual judgment code input means or the calculation result B3 ofthe individual code calculating means is sequentially updated andwritten as the individual code A22 in the individual code memory M22. Adifferent individual code A22 is thus used each time the secondinoperable state is canceled. Therefore, the individual code A22 uniqueto the electronic apparatus is changed each time the second inoperablestate is canceled. For this reason, the individual code A22 used tocancel the previous inoperable state cannot be used again, whereby theftprevention can be enhanced more securely.

According to the present invention, each time the second inoperablestate is canceled, the individual code A22 stored in the individual codememory M22 is updated by writing the calculation result B3 obtained bythe individual code calculating means or the value identical thereto,that is, the calculation result B2 obtained by the dealer-usecalculating means and notified by the dealer to the user. This furtherenhances the effect of theft prevention.

According to the present invention, when the user inputs the individualjudgment code B2 in a wrong manner, and the individual code relationshipmeans thereby judges that the wrong individual judgment code B21 inputby the input means and the individual code A22 do not have apredetermined second relationship, the inoperable state canceling meansdo not cancel the inoperable state against theft. When such a wrongindividual judgment code B21 is input and it is judged by the individualcode relationship judging means that the second relationship is notestablished, the individual code A22 is rewritten and updated on thebasis of the predetermined calculation. As a result, it is possible toenhance the security function furthermore.

Furthermore, in the present invention, the electronic apparatus having asecurity function is characterized in that, when an identification codeA21 previously stored in a nonvolatile identification code memory M21and a judgment identification code C1 input by the input operation ofidentification code input means have a predetermined judgmentidentification relationship, a predetermined operation of the controlledcircuit is enabled, and when the identification code A21 stored in theidentification code memory M21 and the input judgment identificationcode C1 do not have the judgment identification relationship, theelectronic apparatus is put into an inoperable state for confirmation inwhich the predetermined operation of the controlled circuit is disabled.When a predetermined condition relating to the input operation of theidentification code input means is established, the theft judging meansjudges that the electronic apparatus has been exposed to theft, and theinoperable state setting means do not enable the predetermined operationof the controlled circuit after the theft judging means judges that theelectronic apparatus has been exposed to theft, regardless of the inputoperation of the identification code C1.

The present invention provides an electronic apparatus having a securityfunction, wherein when an identification code A21 previously stored in anonvolatile identification code memory M21 and a judgment identificationcode C1 input by the input operation of identification code input meanshave a predetermined identification judgment relationship, apredetermined operation of a controlled circuit is enabled, and when theidentification code A21 stored in the identification code memory M21 andthe input judgment identification code C1 do not have the identificationjudgment relationship, the electronic apparatus is put into a firstinoperable state in which the predetermined operation of the controlledcircuit is disabled. The apparatus comprises: condition judging meansfor judging whether a predetermined condition relating to the inputoperation of the identification code input means is established;inoperable state setting means, in response to an output of thecondition judging means, for, when the condition is established, puttingthe electronic apparatus into a second inoperable state in which thepredetermined operation of the controlled circuit is disabled,regardless of the input operation of the identification code C1 afterthe establishment of the condition; a nonvolatile individual code memoryM22 for storing an individual code A22 individually assigned to theelectronic apparatus; input means for inputting an individual judgmentcode B2; individual code calculating means for carrying outpredetermined individual code calculation by using the individual codeA22; individual code relationship judging means for judging whether theindividual judgment code B2 and a code B3 indicating the calculationresult from the individual code calculating means have a predeterminedindividual judgment relationship; and inoperable state canceling means,in response to an output of the individual code relationship judgingmeans, for canceling the second inoperable state when it is judged thatthe individual judgment code B2 and the code B3 indicating thecalculation result from the individual code calculating means have thepredetermined individual judgment relationship.

According to the present invention, the electronic apparatus may be, forexample, an audio apparatus, such as a compact disc reproductionapparatus, a radio receiver, a magnetic tape reproduction apparatus or atelevision set, mounted on a vehicle, such as a car, or may be anothertype of electronic apparatus. When a power source, such as a battery, isconnected to the electronic apparatus and electric power is suppliedthereto, or when electric power is supplied from a battery to someelectric circuits constituting the electronic apparatus at all times,and electric power is supplied to the remaining circuits thereof byturning on an ignition switch for supplying electric power to theignition circuit of the internal combustion engine of a car and byturning on the power switch of the apparatus, the user inputs thejudgment identification code C1 by the input operation through theidentification code input means. When this input judgment identificationcode C1 and the identification code A21 previously stored in thenonvolatile identification code memory M21 have the predeterminedidentification judgment relationship, for example, when theidentification code A21 of the identification code memory M21 isidentical to the input judgment identification code C1, the controlledcircuit included in the electronic apparatus can carry out itspredetermined operation. The controlled circuit is a compact discreproduction means 11, a radio receiving means 13, a magnetic tapereproduction means 12 or a television receiving means of an electronicapparatus, for example. The expression “the controlled circuit can carryout the predetermined operation” means that the controlled circuit cancarry out its intrinsic operation.

When the judgment identification code C1 input by the identificationcode input means and the identification code A21 previously stored inthe identification code memory M21 do not have the predeterminedidentification judgment relationship, for example, when they are notidentical to each other, the controlled circuit does not carry out thepredetermined operation, and the electronic apparatus is forcibly set tothe first inoperable state. In the electric apparatus controlled in thisfirst inoperable state, when the input judgment identification code C1and the identification code A21 of the identification code memory M21have the predetermined identification judgment relationship, the firstinoperable state is canceled, and the controlled circuit can carry outits predetermined operation as described above.

The condition judging means judges whether the predetermined conditionrelating to the input operation of the identification code input meansis established. For example, when the judgment identification code C1input by the input operation of the identification code input means andthe identification code A21 of the identification code memory M21 do nothave the identification judgment relationship, and when the judgmentidentification code C1 without the identification judgment relationshipis input a predetermined number of times, for example, once or pluraltimes, it is judged that the predetermined condition is established.This predetermined condition is the same as the condition obtained bythe input operation of the identification code input means carried outin the event that the electronic apparatus is stolen. For this reason,the condition judging means may be theft judging means for judging thatthe electronic apparatus is stolen, or that the input operation of theidentification code input means, equivalent to theft, is carried out.

When the predetermined condition is established, the inoperable statesetting means sets the second inoperable state so that the controlledcircuit does not carry out its predetermined operation. Thepredetermined operation of the controlled circuit in the above-mentionedfirst inoperable state may be identical to or different from thepredetermined operation of the controlled circuit in the secondinoperable state. Once the electronic apparatus is forcibly set to thesecond inoperable state, even when the judgment identification code C1having the predetermined identification judgment relationship with theidentification code A21 of the identification code memory M21 is inputthrough the identification code input means, for example, the secondinoperable state cannot be canceled, regardless of the input operationof the identification code C1. The second inoperable state of thepresent invention corresponds to the dealer carry-in mode describedabove in relation to the prior arts.

According to the present invention, the identification code A22 fortheft prevention, unique to the electronic apparatus, is recorded in thenonvolatile individual code memory M22. When the predetermined conditionis established such that the electronic apparatus has been exposed totheft or an equivalent, the individual judgment code B2 notified by thedealer to the user on the basis of the individual code A22 stored in theindividual code memory M22 is input by the user through the individualjudgment code input means, for example. When the individual judgmentcode B2 input as described above and the code B3 indicating thecalculation result obtained by the predetermined individual codecalculation of the individual code A22 in the electronic apparatus havethe predetermined individual judgment relationship, for example, whenthey are identical to each other, the second inoperable state can becanceled. For this reason, the user is not required to carry theelectronic apparatus in the dealer to cancel the second inoperable stateof the electronic apparatus. This eliminates the need for effort andcost for carrying-in.

The present invention further comprises output means for reading theindividual code A22 from the individual code memory M22 and outputtingthe code A22.

The output means of the present invention is indication means.

According to the present invention, the individual code A22 individuallyassigned to each product of the electronic apparatus is stored in thenonvolatile individual code memory M22 so as to be used to cancel thesecond inoperable state of the electronic apparatus controlled so as tobe set at the second inoperable state. The stored individual code A22undergoes the predetermined individual code calculation by theindividual code calculating means provided in the electronic apparatus,and the code B3 indicating the result of the calculation is obtained.

The user of the electronic apparatus inputs the individual judgment codeB2 unique to each product of the electronic apparatus owned by the userthrough the individual judgment code input means. In an embodimentdescribed later, the individual judgment code B2 is obtained when theindividual code A22 stored in the individual code memory M22 is read bythe user through the output means, such as the indication means, andnotified to the dealer, and then the dealer carries out the samecalculation as the predetermined individual code calculation carried outthrough the individual code calculating means.

Although the output means may be the indication means, it may have aconfiguration wherein the individual code A22 stored in the individualcode memory M22 is derived as an electrical signal and transferred tocalculating means, such as a microcomputer or a personal computer,provided in the dealer. The calculating means of the dealer receives thesignal from the output means and carries out the predeterminedindividual code calculation as described above.

In another embodiment of the present invention,

The following may be enabled: the individual code A22 stored in theindividual code memory M22 is read by using a microcomputer or apersonal computer, for example; the individual code A22 having been readis supplied to the dealer; the dealer carries out the same calculationas the predetermined individual code calculation by using the individualjudgment code A22; and the individual judgment code B2 obtained in thisway is notified by the dealer to the user. When obtaining the individualjudgment code B2 from the individual code A22 by calculation, the dealermay use calculating means, such as a microcomputer or a personalcomputer. The dealer may carry out the calculation manually, or anothermethod may be used for the calculation. The predetermined individualcode calculation method carried out by using the individual codecalculating means and the predetermined individual code calculationmethod being similar thereto and carried out by the dealer as describedabove are disclosed to only the dealer and not disclosed to the user andothers.

For example, when the individual code relationship judging means judgesthat the individual judgment code B2 notified by the dealer to the useras described above, and input through the individual judgment code inputmeans and the code B3 indicating the calculation result of theindividual code calculating means have the predetermined individualjudgment relationship, for example, when they are identical to eachother, the inoperable state canceling means cancels the above-mentionedsecond inoperable state, and the predetermined operation of thecontrolled circuit can be carried out.

The individual code A22 may be the calculation result B1 obtained by thepredetermined production number calculation of the production number A12unique to the electronic apparatus. In another embodiment of the presentinvention, the individual code A22 may be the production number A12itself or another code.

The identification judgment relationship is not limited that the codeA21 is identical to the code C1, and the individual judgmentrelationship is not limited that the code B2 is identical to the codeB3. The codes may be values satisfying equations for predeterminedcalculations.

According to the present invention, the individual code A22 stored inthe individual code memory M22 is notified to the dealer through theoutput means, for example. The dealer carries out the predeterminedindividual code calculation by using the individual code A22 asdescribed above. The output means may output the individual code A22 ina state where the user can know, or may output the code A22 to thedealer or the like in a state where the user cannot know.

According to the present invention, the electronic apparatus furthercomprises the indication means as the output means. Therefore, theindividual code A22 stored in the individual code memory M22 isindicated by the indication means, such as visual indication means oraudio notification means, whereby the individual code A22 can benotified to the dealer easily, for example.

The present invention further comprises: a power shut-off detectionmeans for detecting the shut-off state of electric power to theelectronic apparatus; and a nonvolatile power shut-off memory, inresponse to an output of the power shut-off means, for writably storingthe power shut-off state when power shut-off is detected, and thecondition judging means comprises: count means for counting the numberof times the judgment identification code C1 not having theidentification judgment relationship is input through the identificationcode input means; and condition establishment judging means for judgingthat the predetermined condition is established when the power shut-offstate is stored in the power shut-off memory and the count value is notless than a predetermined value N1, in response to the outputs of thepower shut-off memory and the count means.

According to the present invention, when the electronic apparatus isremoved from a car, for example, electric power supplied from the powersource such as a battery to the electronic apparatus is shut off. Thispower shut-off is detected by the power shut-off detection means, andwritten in the nonvolatile power shut-off memory. Furthermore, thejudgment identification code C1 is input by the input operation of theidentification code input means to cancel the first inoperable state.When the input judgment identification code C1 and the identificationcode A21 previously stored in the identification code memory M21 do nothave the identification judgment relationship, the number of inputs iscounted by the count means. In the electronic apparatus which wasexposed to theft, a power shut-off state is written in the powershut-off memory. When the stolen electronic apparatus is connected againto the power source, and the count value reaches the predetermined valueN1 or more, it is judged that the predetermined condition isestablished. As a result, the controlled circuit of the electronicapparatus is controlled so as to be set to the second inoperable state.The predetermined value N1 may be 5 or 10.

According to the present invention, when electric power is shut offbecause the lines for supplying electric power between the battery andthe electronic apparatus are broken or because the connectortherebetween is disconnected in the event that the electronic apparatusis stolen, the power shut-off state is stored in the power shut-offmemory. Furthermore, when the authorized judgment identification code C1is not input through the identification code input means, even wheninput is attempted the predetermined N1 times or more, the predeterminedcondition is established. Therefore the electronic apparatus is judgedas having been exposed to theft, and is forcibly put into the secondinoperable state. In this way, the electronic apparatus is judged ashaving been exposed to theft, and theft prevention becomes effective.When the same operation as that judged that the predetermined conditionis established and that theft is caused is conducted by the user, theelectronic apparatus falls into the second inoperable state. This secondinoperable state can be canceled as described above.

In addition, the present invention further comprises: a nonvolatilefixed value memory for storing a predetermined fixed values forcalculation having plural digits, and the individual code calculatingmeans is characterized in that every digit of a value having pluraldigits relating to the individual code A22 and every corresponding digitof the fixed value are subjected to logical calculation.

According to the present invention, the fixed value for calculationstored in the fixed value memory, not disclosed to the user and thelike, is used for logic calculation when the predetermined individualcode calculation is carried out by using the individual code calculatingmeans to cancel the second inoperable state of the electronic apparatus.Therefore, the calculation procedure or calculation equation forobtaining the code B3 from the individual code A22 is far more preventedfrom being known by a third party. Theft prevention can thus be ensuredmore securely.

According to the present invention, a predetermined fixed value A13 forcalculation having plural digits is used for the calculation forobtaining the code B3 having the identification judgment relationshipwith the individual judgment code B2. Since the fixed value forcalculation is stored in the fixed value memory and not disclosed, thepredetermined individual code calculation can be prevented from beingknown. The effect of theft prevention can thus be more enhanced.

Furthermore, in the present invention, the electronic apparatus having asecurity function is characterized in that the controlled circuit is anaudio apparatus mounted on a vehicle.

Furthermore, the controlled circuit of the present invention is an audioapparatus mounted on a vehicle.

According to the present invention, the electronic apparatus includingthe controlled circuit to be set to the first and second inoperablestates may be an audio apparatus, such as a compact disc reproductionapparatus, a radio receiver, a magnetic tape reproduction apparatus, atelevision set or the like. Since the electronic apparatus is mounted ona vehicle, such as a car, it has a relatively high possibility of beingstolen.

However, this invention can prevent the apparatus from being stolen.

According to the present invention, the present invention is applied tothe audio apparatus mounted on a vehicle, such as a car. Therefore, theapparatus mounted on the vehicle, being prone to be stolen, can beprevented from being stolen.

Furthermore, the present invention provides a dealer-use calculationdevice, comprising deriving means for deriving the individual judgmentcode B2 having a predetermined third relationship with the output codeA221 out of the output code A221 in the electronic apparatus having asecurity function.

According to the present invention, in the dealer-use calculationdevice, the deriving means derives the individual judgment code B2having a predetermined first relationship by subjecting the output codeA221 obtained from the output means of the electronic apparatus tocalculation.

The present invention provides a dealer-use calculation device forcanceling the inoperable state of an electronic apparatus having asecurity function. The electronic apparatus has such a security functionthat the predetermined operation of a controlled circuit is enabled whenan identification code A21 previously stored in a nonvolatileidentification code memory M21 and a judgment identification code C1input by the input operation of identification code input means have apredetermined identification judgment relationship. The controlledcircuit is controlled to enter a first inoperable state so as not tocarry out the above-mentioned predetermined operation when theidentification code A21 stored in the identification code memory M21 andthe input judgment identification code C1 do not have the identificationjudgment relationship. The electronic apparatus comprises: conditionjudging means for judging whether a predetermined condition relating tothe input operation of the identification code input means isestablished; inoperable state setting means, in response to an output ofthe condition judging means, for putting the electronic apparatus into asecond inoperable state in which the predetermined operation of thecontrolled circuit is disabled when the condition is established,regardless of the input operation of the identification code C1 afterthe establishment of the condition; a nonvolatile individual code memoryM22 for storing an individual cod A22 individually assigned to theelectronic apparatus; first indication means for reading the individualcode A22 from an individual code memory M22 and indicating the code A22;first input means for inputting an individual judgment code B2;individual code calculating means for carrying out predeterminedindividual code calculation by using the individual code A22; individualcode relationship judging means for judging whether the individualjudgment code B2 and a code B3 indicating the calculation result fromthe individual code calculating means have a predetermined individualjudgment relationship; and inoperable state canceling means, in responseto an output of the individual code relationship judging means, forcanceling the second inoperable state when it is judged that theindividual judgment code B2 and the code B3 indicating the calculationresult from the individual code calculating means have the predeterminedindividual judgment relationship. The dealer-use calculation devicecomprises: second input means for inputting a dealer-use individualcode; dealer-use calculating means for subjecting the dealer-useindividual code from the second input means to the same calculation asthe predetermined calculation of the individual code calculating means;and second indication means for indicating the calculation result of thedealer-use calculating means.

The present invention provides a dealer-use calculation device forcanceling the inoperable state of an electronic apparatus having asecurity function, wherein the electronic apparatus comprises: theftjudging means for judging that the electronic apparatus has been exposedto theft or an equivalent is carried out; inoperable state settingmeans, in response to the output of the theft judging means, fordisabling a predetermined operation of a controlled circuit when theelectronic apparatus is judged as having been exposed to theft; anonvolatile individual code memory M22 for storing an individual codeA22 individually assigned to the electronic apparatus; first indicationmeans for reading the individual code A22 from the individual codememory M22 and indicating the code A22; first input means for inputtingan individual judgment code B2; individual code calculating means forcarrying out predetermined individual code calculation by using theindividual code A22; individual code relationship judging means forjudging whether an individual judgment code B2 and a code B3 indicatingthe calculation result from the individual code calculating means have apredetermined individual judgment relationship; and inoperable statecanceling means, in response to the output of the individual coderelationship judging means, for canceling an inoperable state when it isjudged that the individual judgment code B2 and the code B3 indicatingthe calculation result from the individual code calculating means havethe individual judgment relationship. The dealer-use operation devicecomprises: second input means for inputting a dealer-use individualcode;

dealer-use calculating means for subjecting the dealer-use individualcode from the second input means to the same calculation as thepredetermined calculation of the individual code calculating means; andsecond indication means for indicating the calculation result of thedealer-use calculating means.

When the authorized user carried out an operation equivalent to theft,for example, and the electronic apparatus has fallen into the secondinoperable state wherein its controlled circuit is made inoperable, thissecond inoperable state is notified to the dealer. At the dealer, thesame calculation as the predetermined individual code calculation by theindividual code calculating means provided for the electronic apparatusis carried out by using the dealer-use calculation device according tothe present invention installed in a store for selling the electronicapparatus or in a workshop for repairing the apparatus. The calculationresult of the dealer-use operation means, that is, the individualjudgment code B2 for canceling the second inoperable state of theelectronic apparatus, can be notified to the user.

According to the present invention, when the electronic apparatus isforcibly set to the second inoperable state wherein the controlledcircuit thereof is made inoperable, the user can cancel the secondinoperable state without carrying the electronic apparatus in thedealer, as described above.

According to the present invention, when the electronic apparatus havingthe security function has fallen into the second inoperable state, theindividual judgment code B2 is notified by the dealer to the user byusing the dealer-use calculation device that the dealer or the likeowns. By using this code, the user can cancel the second inoperablestate without carrying the electronic apparatus in the dealer.

Furthermore, the present invention provides a method of canceling aninoperable state of an electronic apparatus having a security function.The method comprises: preparing an electronic apparatus having asecurity function. The electronic apparatus comprises: theft judgingmeans for judging the apparatus as having been exposed to theft;inoperable state setting means, in response to an output of the theftjudging means, for, when the electronic apparatus is judged as havingbeen exposed to theft, putting the electronic apparatus into aninoperable state against theft in which the predetermined operation ofthe controlled circuit is disabled; a nonvolatile individual code memoryM22 for storing an individual code A22 individually assigned to theelectronic apparatus; output means for outputting an output code A221having a predetermined first relationship with the individual code A22;input means for inputting an individual judgment code B2; individualcode relationship judging means for judging whether the individualjudgment code B2 input by the input means and the individual code A22have a predetermined second relationship; and inoperable state cancelingmeans for, when it is judged by the individual code relationship judgingmeans that the individual judgment code B2 and the individual code A22have the predetermined second relationship, canceling the inoperablestate against theft of the controlled circuit, wherein the individualjudgment code B2 and the individual code A22 have the predeterminedsecond relationship when the output code A221 and the individualjudgment code B2 have a predetermined third relationship. Preparing adealer-use calculation device comprises deriving means for deriving theindividual judgment code B2 having the predetermined third relationshipwith the output code A221 out of the supplied output code A221, whereinthe output code A221 output from the output means of the electronicapparatus having a security function is supplied to the dealer-usecalculation device, and the individual judgment code B2 derived in thedealer-use calculation device and having the predetermined thirdrelationship with the output code A221 is input to the input means ofthe electronic apparatus having a security function.

According to the method of canceling the inoperable state of anelectronic apparatus having a security function of the presentinvention, the output code A221 output from the output means of theelectronic apparatus is supplied to the dealer-use calculation device,the individual judgment code B2 is thereby calculated and derived by thederiving means included in the dealer-use calculation device, and theindividual judgment code B2 is input by the input means of theelectronic apparatus and supplied to the individual code relationshipjudging means, so that the inoperable state against theft of thecontrolled circuit of the electronic apparatus can be canceled by theinoperable state canceling means.

Furthermore, in the method of canceling the inoperable state of theelectronic apparatus having a security function, the electronicapparatus having a security function is characterized in that, when theidentification code A21 previously stored in the nonvolatileidentification code memory M21 and the judgment identification code C1input by the input operation of the identification code input means havethe predetermined judgment identification relationship, thepredetermined operation of the controlled circuit is enabled, and whenthe identification code A21 stored in the identification code memory M21and the input judgment identification code C1 do not have the judgmentidentification relationship, the electronic apparatus is put into aninoperable state for confirmation in which the predetermined operationof the controlled circuit is disabled. When a predetermined conditionrelating to the input operation of the identification code input meansis established, the theft judging means judges that the electronicapparatus has been exposed to theft. Further, the inoperable statesetting means do not enable the predetermined operation of thecontrolled circuit after the theft judging means judges the electronicapparatus as having been exposed to theft, regardless of the inputoperation of the identification code C1.

Furthermore, the present invention provides a method of canceling theinoperable state of an electronic apparatus, in which an electronicapparatus having a security function is prepared, in which thepredetermined operation of a controlled circuit is enabled when anidentification code A21 previously stored in a nonvolatileidentification code memory M21 and a judgment identification code C1input by the input operation of identification code input means have apredetermined identification judgment relationship, and the controlledcircuit is controlled to enter a first inoperable state so as not tocarry out the above-mentioned predetermined operation when theidentification code A21 stored in the identification code memory M21 andthe input judgment identification code C1 do not have the identificationjudgment relationship. The electronic apparatus comprises: conditionjudging means for judging whether a predetermined condition relating tothe input operation of the identification code input means isestablished; inoperable state setting means, in response to an output ofthe condition judging means, for, when the condition is established,putting the electronic apparatus into a second inoperable state in whichthe predetermined operation of the controlled circuit is disabledregardless of the input operation of the identification code C1 afterthe establishment of the condition; a nonvolatile individual code memoryM22 for storing an individual cod A22 individually assigned to theelectronic apparatus; first indication means for reading the individualcode A22 from an individual code memory M22 and indicating the code A22;first input means for inputting an individual judgment code B2;individual code calculating means for carrying out predeterminedindividual code calculation by using the individual code A22; individualcode relationship judging means for judging whether the individualjudgment code B2 and a code B3 indicating the calculation result fromthe individual code calculating means have a predetermined individualjudgment relationship; and inoperable state canceling means, in responseto an output of the individual code relationship judging means, forcanceling the second inoperable state when it is judged that theindividual judgment code B2 and the code B3 indicating the calculationresult from the individual code calculating means have the predeterminedindividual judgment relationship. Furthermore, a dealer-use calculationdevice is prepared. The dealer-use calculation device comprises: secondinput means for inputting a dealer-use individual code; dealer-usecalculating means for subjecting the dealer-use individual code from thesecond input means to the same calculation as the predeterminedcalculation of the individual code calculating means; and secondindication means for indicating the calculation result of the dealer-usecalculating means. The method of canceling the inoperable state of anelectronic apparatus is characterized in that: the individual code A22indicated by the first indication means is input by the second inputmeans; and the calculation result of the dealer-use calculating means,indicated by the second indication means, is input by the first inputmeans.

Furthermore, the present invention provides a method of canceling theinoperable state of an electronic apparatus. The method comprisespreparing an electronic apparatus having a security function andpreparing a dealer-use calculation device. The preparing an electronicapparatus having a security function comprises: theft judging means forjudging that the electronic apparatus has been exposed to theft or anequivalent; inoperable state setting means, in response to an output ofthe theft judging means, for putting the electronic apparatus into aninoperable state in which a predetermined operation of a controlledcircuit is disabled when the electronic apparatus is judged as havingbeen exposed to theft; a nonvolatile individual code memory M22 forstoring an individual code A22 individually assigned to the electronicapparatus; first indication means for reading the individual code A22from the individual code memory M22 and indicating the code A22; firstinput means for inputting an individual judgment code B2; individualcode calculating means for carrying out predetermined individual codecalculation by using the individual code A22; individual coderelationship judging means for judging whether an individual judgmentcode B2 and a code B3 indicating the calculation result from theindividual code calculating means have a predetermined individualjudgment relationship; and inoperable state canceling means, in responseto an output of the individual code relationship judging means, forcanceling an inoperable state when it is judged that the individualjudgment code B2 and the code B3 indicating the calculation result fromthe individual code calculating means have the individual judgmentrelationship. The preparing a dealer-use calculation device comprises:second input means for inputting a dealer-use individual code;dealer-use calculating means for subjecting the dealer-use individualcode from the second input means to the same calculation as thepredetermined calculation of the individual code calculating means; andsecond indication means for indicating the calculation result of thedealer-use calculating means. The individual code A22 indicated by thefirst indication means is input by the second input means, and thecalculation result of the dealer-use calculating means, indicated by thesecond indication means, is input by the first input means.

According to the present invention, when the controlled circuit isforcibly set to the second inoperable state so as not to carry out itspredetermined operation in the event that the electronic apparatushaving the security function has been exposed to theft or an equivalent,the individual code A22 unique to the electronic apparatus and stored inthe individual code memory M22 is read by the user and indicated on thefirst indication means to cancel the second inoperable state. Theindividual code A22 indicated on the first indication means is notifiedby the user to the dealer by telephone, for example. The individual codeA22 notified by the user is input as a dealer-use individual code by thedealer through the second input means of the dealer-use calculatingmeans. By using this code, the dealer-use calculating means carries outthe same calculation as the predetermined individual code calculationcarried out by the individual code calculating means provided for theelectronic apparatus. The result of the calculation is indicated on thesecond indication means of the dealer-use calculation device. Thiscalculation result indicated on the second indication means is notifiedby the dealer to the user by telephone, for example. The calculationresult notified by the dealer and indicated on the second indicationmeans is input as the individual judgment code B2 by the user throughthe first input means of the electronic apparatus. The individual codecalculating means of the electronic apparatus carries out thepredetermined individual code calculation by using the individual codeA22 stored in the individual code memory M22 and indicated on the firstindication means. The individual code relationship judging means judgeswhether the result of the calculation and the individual judgment codeB2 input through the first input means have the predetermined individualjudgment relationship, for example, whether they are identical to eachother. When it is judged that the calculation result obtained by theindividual code calculating means of the electronic apparatus and theindividual judgment code B2 notified by the dealer and input through thefirst input means have the individual judgment relationship, the secondinoperable state is canceled.

According to the present invention, the individual code A22 unique tothe electronic apparatus and indicated on the first indication means isrecognized by the user and notified to the dealer, for example. Theindividual judgment code B2 indicated on the second indication means isrecognized by the dealer and notified to the user. The individualjudgment code B2 is input by the user through the first input means. Asa result, the second inoperable state of the electronic apparatus iscanceled. As described above, the calculation by using the dealer-usecalculation device provided for the dealer and the like must be carriedout once to cancel the second inoperable state of the electronicapparatus. This makes it possible to prevent theft, that is, theelectronic apparatus can be prevented from being stolen.

BRIEF DESCRIPTION OF THE DRAWINGS

Other and further objects, features, and advantages of the inventionwill be more explicit from the following detailed description taken withreference to the drawings wherein:

FIG. 1 is a block diagram showing the configuration of a vehicle-mountedaudio apparatus 1 in accordance with an embodiment of the presentinvention;

FIG. 2 is a simplified external perspective view showing the audioapparatus 1;

FIG. 3 is a flowchart showing the main routine of the operation carriedout by a processing circuit 5;

FIG. 4 is a flowchart illustrating the operation carried out by theprocessing circuit 5 in the identification code setting mode at step u3of FIG. 3;

FIG. 5 is a flowchart illustrating apart of the operation carried out bythe processing circuit 5;

FIG. 6 is a flowchart illustrating the operation carried out by theprocessing circuit 5 in the identification code cancel mode shown inFIG. 3;

FIG. 7 is a flowchart illustrating the operation carried out by theprocessing circuit 5 in the first inoperable state cancel mode at stepu7 of FIG. 3;

FIG. 8 is a flowchart illustrating the operation carried out by theprocessing circuit 5 in the second inoperable state cancel mode at stepu8 of FIG. 3;

FIG. 9 is a flowchart illustrating the operation carried out by theprocessing circuit 5 to cancel the second inoperable state by using anindividual code at step r3 of FIG. 8;

FIG. 10 is a block diagram showing the configuration of a dealer-usecalculation device 28 provided for the dealer;

FIG. 11 is a flowchart illustrating the operation of the calculationcircuit 30 of the dealer-use calculation device 28 shown in FIG. 10;

FIG. 12 is a view illustrating a predetermined calculation for theproduction number A12, executed at step f5 of FIG. 9 by the processingcircuit 5; and

FIG. 13 is a view illustrating a predetermined calculation for theindividual code A22, attained at step f11 of FIG. 9 by the processingcircuit 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now referring to the drawings, preferred embodiments of the inventionare described below.

FIG. 1 is a block diagram showing the configuration of a vehicle-mountedaudio apparatus 1 in accordance with an embodiment of the presentinvention. This audio apparatus 1 is mounted on a vehicle, such as acar. Electric power from a power source 2, such as a battery, issupplied to a processing circuit 5 embodied by a microcomputer or thelike from a line 3 via a disconnectable connector 4, and also suppliedto the processing circuit 5 from an ignition switch 6 via a line 7, theconnector 4 and lines 23, 24. Furthermore, the electric power suppliedfrom the line 7 via the connector 4 is supplied to an indication means10 from a line 8 via a switch 9, and also supplied to a compact disc(abbreviated as CD) reproduction means 11, a magnetic tape reproductionmeans 12 and a radio/television set 13. Audio signals from these means11, 12 and 13 are amplified by an amplifier circuit 14 to drive aspeaker 15 via a switching means 36.

FIG. 2 is a simplified external perspective view showing the audioapparatus 1. In this embodiment, the indication means 10 is used toindicate the operation information of the compact disc reproductionmeans 11 and the contents recorded on a compact disc, and is also usedto indicate operation related to a security function in accordance withthe present invention. A power switch 16 is connected to the processingcircuit 5. By pressing the power switch 16 to turn it on while electricpower is supplied to the audio apparatus 1 via the ignition switch 6,the switch 9 is brought into conduction, and the audio apparatus 1enters its operation state. The operation state of the audio apparatus 1can be stopped by pressing the power switch 16 to turn it off. Theignition switch 6 supplies/shuts off the electric power of the powersource 2 to the ignition circuit 34 and the starter motor 35 of theinternal combustion engine, such as the spark-ignition internalcombustion engine of a vehicle. An input means 17 is used to control theintrinsic compact disc reproduction operation of the compact discreproduction means 11, and is also used to control the security functionin accordance with the present invention.

Furthermore, a random-access memory RAM 18 for calculation is connectedto the processing circuit 5.

A non-erasable nonvolatile read-only memory 19 and a writablenonvolatile memory 21 are also connected to the processing circuit 5.The memory 21 is an EEPROM (Electrically Erasable Programmable Read OnlyMemory). The contents stored in the memories 19, 21 are retained evenwhen electric power from the power source 2 is shut off. A master codeA11 is stored in the memory area Mi1 of the memory 19. A uniqueproduction number A12 assigned to each product of the audio apparatus 1is stored in the memory area M12. A fixed value A13 for carrying out apredetermined individual code calculation described later is stored inthe memory area M13.

An identification (abbreviated as ID) code A21 is stored in the memoryarea M21 of the memory 21. This identification code A21 is TOC (Table OfContents) information stored in the lead-in area of a compact discselected by the user and reproduced by the compact disc reproductionmeans 11. An individual code A22 is stored in the memory area M22. Thisindividual code A22 can be updated and written. An individual judgmentcode B2 input through the input means 17 is rewritably stored in thememory area M23. A code B3 indicating the result of the predeterminedindividual code calculation described later is stored in the memory areaM24. Furthermore, data A25 indicating the fact that the disconnectableconnector 4 is disconnected once and electric power to the audioapparatus 1 is shut off is stored in the memory area M25. Data A26indicating the fact that the audio apparatus 1 has fallen into a secondinoperable state described later is stored in the memory area M26.

FIG. 3 is a flowchart showing the main routine of the operation carriedout by the processing circuit 5. At step u1, the state of the connector4 is changed from a disconnection state to a connection state. When thepower switch 16 is turned on, and the audio apparatus 1 enters anoperation state, the operations after step u2 will start as shown inFIG. 3. At step u2, a judgment is made to determine whether theidentification code A21 is set and stored in the memory area M21 of thememory 21. When the identification code A21 is not set, the procedure ofthe routine advances to step u3, and enters an identification codesetting mode.

When it is judged at step u2 that the identification code A21 is set,the procedure advances to the next step u4. At step u4, a judgment ismade to determine whether the data A25 indicating that the power sourceis shut off once because of the disconnection of the connector 4 forconnecting the audio apparatus 1 to the power source 2 or the break ofthe line 3 is stored in the memory area M25. When the data indicatingpower shut-off is not stored in the memory area M25, the procedureenters an identification code cancel mode at the next step u5. When thedata A26 indicating power shut-off is stored in the memory area M25, theaudio apparatus 1 has fallen into a first or second inoperable state.The procedure advances to step u6, and a judgment is made to determinewhether data indicating the second inoperable state is stored in thememory area M26. When it is judged at step u6 that the data indicatingthe second inoperable state is not stored, it is indicated that theaudio apparatus 1 is in the first inoperable state. The procedure thenadvances to step u7 and enters the mode for canceling this firstinoperable state.

The first inoperable state is also referred to as an inoperable statefor confirmation, and the second inoperable state is also referred to asan inoperable state against theft. These first and second inoperablestates may be identical to or different from each other.

The processing circuit 5 always monitors the voltage on the line 23directly connected to the power source 2. When the monitored voltagedrops below a predetermined value, it is judged that power shut-off iscaused. Data indicating this power shut-off is stored in the memory areaM25.

When data indicating the second inoperable state is stored in the memoryarea M26, the procedure advances to step u8 and enters the mode forcanceling the second inoperable state.

FIG. 4 is a flowchart illustrating the operation carried out by theprocessing circuit 5 in the identification code setting mode at step u3of FIG. 3. The identification code is sometimes referred to as an ID(identification) code. The procedure advances from step s1 to step s2,and a judgment is made to determine whether a mode-off operation hasbeen carried out. When the mode-off operation has been carried out, theprocedure advances to step s4. At this step, the ordinary operationprocessing for the intrinsic operation control of the audio apparatus 1is carried out, without setting the identification code A21 into thememory area M21 of the memory 21. The mode-off operation is an operationother than the ID code setting start operation, and is the ordinaryoperation of the audio apparatus 1, such as insertion/ejection of acompact disc, selection of a song, control of volume and tone and thelike.

At step s3, a judgment is made to determine whether an identificationcode setting start operation has been carried out. When the operationhas been carried out, the procedure advances to step s5. Theidentification code setting start operation is a predetermined specificoperation. In the case of the embodiment of the present invention, theoperation is an operation other than the ordinary operation forreproduction of a compact disc, for example, and maybe the simultaneousoperation of a switch for inserting/ejecting a compact disc and a switchfor selecting a first song. At step s5, the compact disc previouslyselected and inserted by the user is reproduced by the compact discreproduction means 11. The TOC (table of contents) information stored inits lead-in area is written and stored as the identification data A21 inthe memory area M21 at the next step s6. At step s7, the ordinaryoperation of the audio apparatus 1 is carried out.

FIG. 5 is a flowchart illustrating a part of the operation carried outby the processing circuit 5. The procedure advances from step v1 to stepv2. In a state wherein the connector 4 is connected, the ignition switch6 is turned on, and electric power is supplied to the processing circuit5 via the lines 23, 24, a judgment is made at step v2 to determinewhether the power switch 16 has been pressed and turned on. When thepower switch 16 has not been turned on, a lamp 25 blinks at step v3.While the audio apparatus 1 does not perform audio operation, that is,while the power switch 16 is turned off, the lamp 25 blinks. By seeingthis blinking of the lamp 25, the thief understands that the audioapparatus 1 has a security function. This prevents the audio apparatusfrom being stolen.

When it is judged at step v2 that the power switch 16 has been turnedon, it is judged at the above-described step u4 of FIG. 3 that the dataA25 indicating the power shut-off is not stored in the memory area M25,that is, the apparatus does not fall into the first inoperable state,and it is judged at step u6 of FIG. 3 that the data A26 indicating thesecond inoperable state is not stored in the memory area M26, theprocedure advances to step v4 in accordance with step s4 of FIG. 4 andstep p3 of FIG. 6, whereby the audio apparatus 1 performs its intrinsicordinary operation, and generates audio output.

When the power switch 16 is not turned on as described above, or theapparatus falls into the first and second inoperable states although thepower switch 16 is turned on, the procedure at step v3 is executed todrive the lamp 25 to blink, and the intrinsic ordinary operation of theaudio apparatus 1 is not carried out. At step v5, a judgment is made todetermine whether power shut-off because of non-supply of power to theprocessing circuit 5 via the line 23 is detected. When the powershut-off is detected, data A25 indicating the power shut-off is storedin the memory area M25 at step v6. At step v7, a series of operationsends.

FIG. 6 is a flowchart illustrating the operation carried out by theprocessing circuit 5 in the identification code cancel mode shown inFIG. 3. The procedure advances from step p1 to step p2, and a judgmentis made to determine whether the mode-off operation has been carriedout. When the mode-off operation has been carried out, the procedureadvances to step p3. At this step, the ordinary operation processing forthe intrinsic operation control of the audio apparatus 1 is carried out.When the mode-off operation has not been carried out at step p2, ajudgment is made at step p4 to determine whether ID code cancel startoperation has been carried out. When the operation has not been carriedout, the procedure advances to step p3. The mode-off operation at stepp2 is an ordinary operation explained with respect to step s2 describedabove referring to FIG. 4. The identification code cancel startoperation at step p4 is a predetermined specific operation. In the caseof the embodiment of the present invention, the operation may be thesimultaneous operation of the compact disc insertion/ejection switch anda switch for selecting a second song from among plural songs recorded onthe compact disc inserted. As described above, this operation is anoperation other than the ordinary operation of the audio apparatus 1.

At step p5, a judgment identification code C1 is input. This judgmentidentification code C1 is TOC information stored in the lead-in area ofa compact disc read by the compact disc reproduction means 11. The user,i.e. the owner of the audio apparatus 1, inserts the same compact discas that used to store the identification code A21 in the above-mentionedmemory area M21 into the compact disc reproduction means 11 to reproducethe compact disc at step p5, whereby the judgment identification codeC1, i.e TOC information, is read out.

At step p6, the judgment identification code C1 having been input atstep p5 is compared with the identification code A21 previously storedin the memory area M21 to judge whether they have a predeterminedidentification judgment relationship, i.e. whether they are identical toeach other, for example. In the case of the present embodiment, when itis judged that the judgment identification code C1 having been input atstep p5 is identical to the identification code A21, the procedureadvances to step p12, and the identification code A21 stored in thememory area M21 is deleted. The procedure then advances to step p13, andordinary operation is carried out.

At the above-mentioned step p6, when it is judged that the judgmentidentification code C1 having been input at step p5 is not identical tothe identification code A21 stored in the memory area M21, the procedureadvances to step p7. At step p7, the number of inconsistencies betweenthe judgment identification code C1 and the identification code A21 iscounted. At step p8, a judgment is made to determine whether theinconsistencies are generated continuously predetermined number oftimes, N1. When the number of inconsistencies is less than N1, theprocedure advances to step p9, and the indication means 10 carries outerror indication. In this error indication, the indication means 10indicates characters “ERR” together with the number of values counted atstep p7 for a predetermined period of time, for example, 2 seconds.After step p9, the procedure returns to step p5.

When the number of errors is not less than the predetermined value N1 atstep p8, data indicating the second inoperable state is set and writtenin the memory area M26 at step p10. This second inoperable state iscanceled at step p11. The value N1 may be 5 or 10, for example.

FIG. 7 is a flowchart illustrating the operation carried out by theprocessing circuit 5 in the first inoperable state cancel mode at stepu7 of FIG. 3. The procedure advances from step q1 to step q2. Steps q2to q8 of FIG. 7 are the same as steps p5 to p11 of FIG. 6. A judgment ismade at step q3 to determine whether the judgment identification code C1input at step q2 and the identification code A21 stored in the memoryarea M21 have an identification judgment relationship, for example,whether they are identical to each other. When not identical, the numberof inconsistencies is counted at step q4. A judgment is made at step q5to determine whether the count value is not less than the predeterminedvalue N2. When the count value is less than N2, the procedure advancesto step q6. At step q6, error indication is carried out, the count valueis indicated for 2 seconds, and the procedure returns to step q2. Whenit is judged at step q5 that the count value is not less than thepredetermined value N2, data indicating the second inoperable state isstored in the memory area M26 at step q7. The second inoperable state iscanceled at step q8.

When it is judged at step q3 that the judgment identification code C1 isidentical to the identification code A21, data indicating powershut-off, stored in the memory area M25, is deleted at the next step q9.The ordinary operation of the audio apparatus 1 is carried out at stepq10. The value N2 at step q5 may be identical to the above-mentionedvalue N1, or may be 5 or 10.

FIG. 8 is a flowchart illustrating the operation carried out by theprocessing circuit 5 in the second inoperable state cancel mode at stepu8 of FIG. 3. The procedure advances from step r1 to step r2. A judgmentis made to determine whether a predetermined specific operation iscarried out by the input means 17. This specific operation is thesimultaneous operation of the compact disc insertion/ejection switch anda switch for selecting a third song, for example. The specific operationmay be switch operation not carried out ordinarily by the audioapparatus 1. When this kind of specific operation is carried out, theprocedure advances to step r3 wherein the second inoperable state iscanceled by using an individual code in accordance with the presentinvention. This step r3 will be described referring to FIG. 9.

Although the setting start operation at step s3 of FIG. 4, the cancelstart operation at step p4 of FIG. 6, and the specific operation at stepr2 of FIG. 8 may be different from each other as described above, theymay be identical to each other.

When the above-mentioned specific operation is not carried out at stepr2 of FIG. 8, the procedure advances to step r6, and a judgment is madeto determine whether the master code A11 has been input. The master codeis held by only the dealer secretly, recorded on the master compact discand controlled so as not to be disclosed. This kind of master compactdisc is inserted into the compact disc reproduction means 11, and themaster code stored in its lead-in area is read for example. At step r7,a judgment is made to determine whether the master code having been readis identical to the master code A11 stored in the memory area M11 of thenon-erasable memory 19. When identical, the identification code A21stored in the memory area M21 of the memory 21 is deleted, and dataindicating the second inoperable state stored in the memory area M26 isalso deleted at step r4. As a result, the ordinary operation of theaudio apparatus 1 can be carried out at step r5.

FIG. 9 is a flowchart illustrating the operation carried out by theprocessing circuit 5 to cancel the second inoperable state by using anindividual code at step r3 of FIG. 8. The procedure advances from stepf1 to step f2. At step f2, a judgment is made to determine whether anindividual code A22 is stored in the memory area M22. This individualcode A22 is a unique code individually assigned to the audio apparatus1. When it is judged that the individual code A22 is not stored in thememory M22 at step f2, the production number A12 is read from the memoryarea M12 at step f3. At step f4, the production number A12 having beenread is indicated by the indication means 10.

At step f5, a predetermined calculation for the production number A12,described later referring to FIG. 12, is carried out by using theproduction number A12 having been read, and a calculation result B1 isobtained. Step f5 forms a production number calculating means. Theproduction number may be input manually through the input means 17. Thecalculation result B1 is stored as the individual code A22 in the memoryarea M22 at step f6. The memory area M12 constitutes a production numbermemory. The memory area M22 constitutes an individual code memory.

At step f7, a value A221 having a predetermined first relationship withthe individual code A22 stored in the memory area M22, such as arelationship of being equal, is indicated by the indication means 10.

At the step f2, when the individual code A22 is judged as being storedin the memory area M22, at step f7 is indicated the value A221 havingthe predetermined first relationship with the individual code A22 storedin the memory area M22, such as a relationship of being equal.

The user of the audio apparatus 1 recognizes the individual code A221indicated by the indication means 10, makes a phone call to the dealerby using a telephone 27 so that the individual code A221 is notified tothe dealer by voice. The dealer receives the individual code A221 asdescribed later referring to FIGS. 10 and 11, and carries outcalculation as described later referring to FIG. 13. In FIG. 9, theoperation at step f8 is described for ease of understanding, althoughthe operation is not carried out by the processing circuit 5. When theindividual judgment code B2 calculated by the dealer is notified by thedealer to the user by voice by the telephone 27, the user inputs theindividual judgment code B2 by using the input means 17.

When it is judged at step f9 that the individual judgment code B2 hasbeen input by using the input means 17, the individual judgment code B2having been input is stored in the memory area M23 at step f10.

At step f11, by using the individual code A22 stored in the memory areaM22, a predetermined individual code calculation is carried out asdescribed later referring to FIG. 13, and the calculation result B3 isobtained and stored in the memory area M24.

At step f12, a judgment is made to determine whether the individualjudgment code B2 having been input and stored in the memory area M23 andthe code B3 obtained by the calculation at step f11, stored in thememory area M24 and indicating the result of the calculation areidentical to each other, that is, there is the predetermined secondrelationship between the individual code A22 stored in the memory areaM22 and the individual judgment code B2 input and stored in the memoryM23.

When the individual judgment code B2 is identical to the code B3indicating the calculation result, at step f13 the code B3 indicatingthe coincident calculation result is read from the memory area M24 andtransferred as the individual code A22 to the memory area M22 so as tobe updated. When not identical at step f12, the procedure returns tostep f9. After step f14, the procedure advances to the above-mentionedstep r4 of FIG. 8.

Step f11 constitutes the individual code calculating means for carryingout the predetermined calculation of the individual code A22. Step f12constitutes the individual code relationship judging means. Step f13constitutes the means for writing and updating the individual code A22.

FIG. 10 is a block diagram showing the configuration of a dealer-usecalculation device 28 provided for the dealer. The dealer has atelephone 32 for telephone communication with the user. In addition, aninput means 29, such as a keyboard, is provided so that the dealer caninput the individual code A221 known from the user by the telephone 32.The output of the input means 29 is supplied to a calculation circuit 30embodied by a microcomputer or the like. The calculation circuit 30carries out the predetermined calculation of the individual code A221 asdescribed later referring to FIG. 13. The code B2 indicating the resultof the calculation is indicated by the indication means 31.

It can be said that the code B2 indicating the calculation resultobtained by the calculation circuit 30 has a predetermined thirdrelationship as shown in FIG. 13, for example, with the individual codeA221 input by the input means, that is, the individual code A221indicated by the indication means. The indication means 31 may have aconfiguration for performing visual indication or audio notificationwith a voice synthesis circuit, for example. This kind of dealer-usecalculation device 28 can be embodied by a personal computer or thelike.

FIG. 11 is a flowchart illustrating the operation of the calculationcircuit 30 of the dealer-use calculation device 28 shown in FIG. 10. Theprocedure advances from step g1 to step g2. When it is judged that theindividual code A221 notified by the telephone 32 has been input throughthe input means 29, the individual code A221 having been input undergoesthe calculation shown in FIG. 13, and the individual judgment code B2 isobtained at the next step g3. At step g4, the individual judgment codeB2, the result of the calculation, is indicated by the indication means31. In this way, a series of operations end at step g5. The individualjudgment code B2 indicated by the indication means 31 is notified fromthe dealer to the user by the telephone 32.

FIG. 12 is a view illustrating a predetermined calculation for theproduction number A12, executed at step f5 of FIG. 9 mentioned above.The calculation shown in FIG. 12 is attained by the processing circuit5. The memory area M12 has storage areas D1 to D8 for each storing eachdigit of a decimal number. The production number A12 is formed of pluraldecimal digits (8 digits in the case of the present embodiment). Whenthe production number A12 is “53649215” for example, a binary number“0101” indicating 5, the value at the most significant digit of thedecimal number, is stored at the most significant digit D8. A binarynumber “0011” indicating 3, the value at the second significant digit ofthe decimal number, is stored at the storage area D7.

The memory area M31 of the random access memory 18 has storage areas J1to J7 for each storing a binary number comprising four digits. Thenumber of digits, the storage areas Ji to J7, is less than that of theabove-mentioned storage areas D1 to D8 by one. The processing circuit 5carries out exclusive OR (EX-OR) for two digits adjacent to each otherin the range of the digits D1 to D8 in the memory area M12. The resultsare written in the storage areas J1 to J7, respectively. For example,the binary numbers in the storage areas D8 and D7 are exclusively ORedat each binary digit, and the result of the calculation is stored in thestorage area J7. In the case of the present embodiment, “0101” in thestorage area D8 and “0011” in the storage area D7 are exclusively ORedat each binary digit, and a binary number “0110” is stored in thestorage area J7. In the same way, “0011” in the storage area D7 and“0110” in the storage area D6 are exclusively ORed, and “0101” is storedin the storage area J6.

The contents of the memory area M31 holding the exclusive OR calculationresults further undergo a second exclusive OR calculation for two digitsadjacent to each other in the range of the storage areas J1 to J7, andthe results are stored in the storage areas K1 to K6 of the memory areaM32, respectively. For example, “0110” in the storage area J7 and “0101”in the storage area J6 are exclusively ORed at each binary digit, andthe result, a binary number “0011,” is stored in the storage area K6. Inthis way, two digits represented in binary and adjacent to each other ofthe decimal production number A12 are exclusively ORed sequentially twotimes in total as described above. As a result, the hexadecimalindividual code B1 is obtained in the memory area M32. The content B1 ofthe memory area M32 obtained as described above is transferred to thememory area M22 of the memory 21 and then written. The memory areas M31and M32 are embodied by the random access memory 18. In the case ofanother embodiment of the present invention, when it is judged at theabove-mentioned step f12 of FIG. 9 that a code B21 different from thecorrect individual judgment code B2 to be input by the input means 17 isinput by mistake, it may be possible to calculate in accordance with apredetermined calculation method to obtain a new individual code A222different from the individual code A22 calculated and obtained at stepf6, and write this new individual code A222 in the memory area M22 toupdate, instead of executing the above-mentioned step f9 of FIG. 9. Inthis way, the individual code A22 stored in the memory area M22 isupdated and a new individual code A222 is obtained, every time when awrong code B21 different from the correct individual judgment code B2 isinput through the input means 17.

The calculation method for such a new individual code A222 is, forexample, to bring the bit “1” at the least significant digit of thebinary value “0111” in the least significant storage area K1 of thememory area M32 shown in FIG. 12 to the position of the bit “0” at themost significant digit of the binary value “0011” in the mostsignificant storage area K6, thereby circulating and shifting a bit ateach binary digit in the storage areas Ki to K6 of the memory area M32to the less significant bit side (the right side of FIG. 12) by one bit.As a result, the binary value in the most significant storage area K6 is“1001,” the binary value in the storage area K5 is “1111,” and finallythe binary value in the least significant storage area K1 is “0011”after this calculation. Such a calculation of shifting and circulatingto the less significant digit by one bit is executed every time when theabove-mentioned second relationship, that is, the individual judgmentrelationship is not established because of a wrong code B21 inputthrough the input means.

In the case of another embodiment of the present invention, to updatethe individual code A22:

(a) the individual code A22 stored in the memory area M22 is subjectedto calculation in accordance with a predetermined logical equation toupdate, every time when the correct or wrong code B21 is input;

(b) calculation is executed in accordance with a preset table; or

(c) a new individual code A222 may be obtained by another calculationmethod.

FIG. 13 is a view illustrating the predetermined calculation for theindividual code A22 attained at step f11 of FIG. 9 by the processingcircuit 5. This calculation is the same as the predetermined individualcode calculation at step g3 of FIG. 11 by the calculation circuit 30included in the dealeruse calculation device 28 shown in FIG. 10. Thiskind of calculation will be described below. In the processing circuit5, the individual code A22 stored in the memory, area M22 has a binaryvalue at each of plural hexadecimal digits, 6 digits of K11 to K16, forexample. This individual code A22 is read, and each binary digit of theabove-mentioned digits K11 to K16 is shifted by one digit to the rightof FIG. 13 to obtain the digits K21 to K26 of the memory area 34. Thebinary value (“1” for example) at the least significant digit of thelast digit K11 is transferred and shifted to the most significant digitof the most significant digit K26 of the memory area M34.

As mentioned above, the fixed value A13 is stored in the memory area M13of the memory 19. This fixed value A13 is a decimal value, “360066” forexample. The number of binary digits of A13 is the same as that of theindividual code A22, and the binary values of A13 are stored and set atdigits K31 to K36.

By the processing circuit 5, the binary values at the digits K21 to K26of the memory area M34 and the corresponding binary values at the digitsK31 to K36 of the memory area M13 are exclusively ORed, respectively.The result values are stored at digits K41 to K46 of the memory areaM36, respectively, the number of digits being the same as those of thememory areas M34 and M13 (six digits in the case of the presentembodiment). The binary digits of the digit K26 and the correspondingbinary digits of the digit K36 are exclusively ORed, respectively, forexample, and the result values of the calculation are stored at thedigit K46. The memory areas M34 and M36 are embodied by the randomaccess memory 18. The obtained result of the calculation in the memoryarea M36 is written and stored as the code B3 in the memory area M24 ofthe memory 21.

The calculation operation of the processing circuit 5, shown in FIG. 13,can also be attained by the calculation circuit 30 of the dealer-usecalculation device 28. The individual code A221 to be input through theinput means 29 is the same as the content stored in the memory area M22of FIG. 13.

In the case of the above-described embodiment, the individual code A22stored in the memory area M22 and the output code A221 indicated by theindication means and supplied to the dealer by telephone, have a firstrelationship, where they are identical to each other. On the other hand,in the case of another embodiment of the present invention, the memory21 shown in FIG. 1 is provided with the memory area M221. Apredetermined calculation is executed by using the individual code A22stored in the memory M22, and the output code A221 is obtained from thecalculation result and stored in the memory area M221. Thus, theindividual code A22 and the output code A221 have a first relationship,which is the above-mentioned predetermined calculation method using theindividual code, and therefore, the value of the output code A221 isdifferent from that of the individual code A22. The output code A221stored in the memory area M221 is indicated and output by the indicationmeans 10 at the above-mentioned step f7 of FIG. 9. The user recognizesthe output code A221 indicated by the indication means 10 and notifiesthe code to the dealer by telephone. The dealer receives the output codeA221 to execute calculation in accordance with the predetermined thirdrelationship and obtain the individual judgment code B2. In the presentinvention, therefore, the value of the output code A221 may be the sameas that of the individual code A22 in accordance with the predeterminedfirst relationship as described in the embodiment shown by the figures,while the value of the output code A221 may be different from that ofthe individual code A22 as a result of a predetermined calculation usingthe individual code A22 in another embodiment.

A still another embodiment of the present invention will be describedbelow. The predetermined first to third relationships in this embodimentare determined as follows. To calculate and obtain the output code A221having a predetermined first relationship with the individual code A22,a calculation is executed such that each bit at the respective digitsK11 to K16 of the individual code A22 stored in the memory M22 isshifted by one bit to the more significant side (i.e., the leftdirection in FIG. 13), and the most significant bit at the mostsignificant digit K16 is transferred to the least significant bit at theleast significant digit K11. In this way, the output code A221 havingthe predetermined first relationship with the individual code A22 isobtained.

To calculate and obtain the code B3 stored in the memory M24, which codeB3 is to be compared with the individual judgment code B2 having apredetermined second relationship with the individual code A22, in thesame way as shown in FIG. 13, a calculation is executed such that eachbit at the respective digits K11 to K16 of the individual code A22 isshifted by one bit to the less significant side (i.e., the rightdirection in FIG. 13), and the least significant bit at the leastsignificant digit K11 is transferred to the most significant bit at themost significant digit K16, and exclusive Or is executed by using afixed value A13 as shown in FIG. 13. The calculation result, which is acontent stored in the memory M36, is made to be the code B3.

The dealer-use calculation device 28 calculates to obtain the code B2having a predetermined third relationship with the output code A221input through the input means 29. In the calculation circuit 30, acalculation is executed such that the plural digits of the output codeA221 are shifted by two bits to the less significant side (i.e., theright direction in FIG. 13) and the least significant bit at the leastsignificant digit is transferred to the most significant bit at the mostsignificant digit, and moreover, exclusive OR is executed by using afixed value A13 as shown in FIG. 13. The calculation result stored inthe memory area M36 is made to be the code B2 in the same way asdescribed above.

In this way, the individual code A22 stored in the memory M22 issubjected to calculation in accordance with the predetermined firstrelationship to obtain the output code A221, and the output code A221 issubjected to calculation in accordance with the predetermined thirdrelationship to obtain the code B2.

This code B2 coincides with the individual judgment code B3 obtained bysubjecting the individual code A22 to calculation in accordance with apredetermined second relationship.

In the case of the above-mentioned embodiment of the present inventionshown by figures, the individual code A22 and the output code A221 havea first relationship, where they have identical values to each other,and the individual judgment code B2 and the individual code A22 have asecond relationship, where they have different values from each other.However, in the case of a still another embodiment of the presentinvention, the output code A221 and the individual code A22 may have afirst relationship, where they have values different from each other,and the individual judgment code B2 and the individual code A22 may havea second relationship, where they have values identical to each other.

In another embodiment of the present invention, AND, OR, or anotherlogic operation may be performed instead of exclusive OR as shown inFIGS. 12 and 13.

The invention can be applied not only to the audio apparatus 1, but alsoto a wide variety of electronic apparatuses having other variousconfigurations.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and the rangeof equivalency of the claims are therefore intended to be embracedtherein.

What is claimed:
 1. An electronic apparatus having a security function,said electronic apparatus comprising: theft judging means for judgingwhether said electronic apparatus has been exposed to theft; inoperablestate setting means for, in response to an output of said theft judgingmeans, putting said electronic apparatus into an inoperable stateagainst the theft in which a predetermined operation of a controlledcircuit is disabled, said electronic apparatus being put into theinoperable state when said theft judging means judges that saidelectronic apparatus has been exposed to the theft; a nonvolatileindividual code memory for storing an individual code individuallyassigned to said electronic apparatus; output means for outputting anoutput code having a predetermined first relationship with theindividual code, the output code being calculated using the individualcode stored in said nonvolatile individual code memory; input means forinputting an individual judgment code, the individual judgment codebeing obtained from the output code and being calculated based on apredetermined third relationship with the output code; individual coderelationship judging means for judging whether the individual judgmentcode inputted by said input means and a code calculated based on theindividual code have a predetermined second relationship; and inoperablestate cancelling means for cancelling the inoperable state against thetheft in which the predetermined operation of the controlled circuit isdisabled, the inoperable state being cancelled when said individual coderelationship judging means judges that the individual judgment code andthe code calculated based on the individual code have the predeterminedsecond relationship.
 2. The electronic apparatus having the securityfunction of claim 1, wherein, when the output code and the individualjudgment code have the predetermined third relationship, the individualjudgment code and the code calculated based on the individual code havethe predetermined second relationship.
 3. The electronic apparatushaving the security function of claim 1, wherein the individual code isa production number of said electronic apparatus.
 4. The electronicapparatus having the security function of claim 1, further comprising: anonvolatile unique memory for storing unique data that is unique to saidelectronic apparatus; and calculating means for carrying out apredetermined calculation using the unique data stored in saidnonvolatile unique memory, and storing a result of the predeterminedcalculation in said nonvolatile individual code memory as the individualcode.
 5. The electronic apparatus having the security function of claim4, wherein the unique data is a production number of said electronicapparatus.
 6. The electronic apparatus having the security function ofclaim 1, wherein in response to the input of the individual judgmentcode by said input means, the individual code is updated by apredetermined calculation.
 7. The electronic apparatus having thesecurity function of claim 1, wherein, when an identification codepreviously stored in a nonvolatile identification code memory and ajudgment identification code inputted by an input operation of anidentification code input means have a predetermined judgmentidentification relationship, the predetermined operation of thecontrolled circuit is enabled, and when the identification code storedin the nonvolatile identification code memory and the inputted judgmentidentification code do not have the predetermined judgmentidentification relationship, said electronic apparatus is put into aninoperable state for confirmation in which the predetermined operationof the controlled circuit is disabled, wherein, when a predeterminedcondition relating to the input operation of said identification codeinput means is established, said theft judging means judges that saidelectronic apparatus has been exposed to the theft, and wherein saidinoperable state setting means does not enable the predeterminedoperation of the controlled circuit after said theft judging meansjudges that said electronic apparatus has been exposed to the theft,regardless of the judgment identification code inputted by saididentification code input means.
 8. The electronic apparatus having thesecurity function of claim 1, wherein the controlled circuit is an audioapparatus mounted on a vehicle.
 9. A dealer-use calculation devicecomprising deriving means for deriving the individual judgment codehaving the predetermined third relationship with the output code, theindividual judgment code being derived from the output code output fromsaid output means of said electronic apparatus of claim
 2. 10. A methodof cancelling an inoperable state of an electronic apparatus having asecurity function, said method comprising: providing the electronicapparatus having the security function, the electronic apparatuscomprising: theft judging means for judging whether the electronicapparatus has been exposed to theft, inoperable state setting means for,in response to an output of the theft judging means, putting theelectronic apparatus into an inoperable state against the theft in whicha predetermined operation of a controlled circuit is disabled, theelectronic apparatus being put into the inoperable state when the theftjudging means judges that the electronic apparatus has been exposed tothe theft, a nonvolatile individual code memory for storing anindividual code individually assigned to the electronic apparatus,output means for outputting an output code having a predetermined firstrelationship with the individual code, input means for inputting anindividual judgment code, individual code relationship judging means forjudging whether the individual judgment code inputted by the input meansand a code calculated based on the individual code have a predeterminedsecond relationship, and inoperable state cancelling means forcancelling the inoperable state against the theft in which thepredetermined operation of the controlled circuit is disabled, theinoperable state being cancelled when the individual code relationshipjudging means judges that the individual judgment code and the codecalculated based on the individual code have the predetermined secondrelationship, wherein the individual judgment code and the codecalculated based on the individual code have the predetermined secondrelationship when the output code and the individual judgment code havea predetermined third relationship; providing a dealer-use calculationdevice to derive the individual judgment code, the dealer-usecalculation device comprising deriving means for deriving the individualjudgment code having the predetermined third relationship with theoutput code, the individual judgment code being derived from the outputcode output from the output means of the electronic apparatus; supplyingthe output code outputted from the output means of the electronicapparatus to the dealer-use calculation device; and inputting theindividual judgment code derived in the dealer-use calculation deviceand having the predetermined third relationship with the output code tothe input means of the electronic apparatus.
 11. The method ofcancelling the inoperable state of the electronic apparatus having thesecurity function of claim 10, further comprising: providing anonvolatile identification code memory for storing an identificationcode of the controlled circuit; and providing an identification codeinput means for inputting a judgment identification code of thecontrolled circuit; wherein, in the electronic apparatus having thesecurity function, (i) when the identification code previously stored inthe nonvolatile identification code memory and the judgmentidentification code inputted by the identification code input means havea predetermined judgment identification relationship, the predeterminedoperation of the controlled circuit is enabled, and (ii) when theidentification code stored in the nonvolatile identification code memoryand the judgment identification code inputted by the identification codeinput means do not have the predetermined judgment identificationrelationship, the electronic apparatus is put into an inoperable statefor confirmation in which the predetermined operation of the controlledcircuit is disabled; wherein, when a predetermined condition relating toan input operation of the identification code input means isestablished, the theft judging means judges that the electronicapparatus has been exposed to the theft; and wherein the inoperablestate setting means does not enable the predetermined operation of thecontrolled circuit after the theft judging means judges that theelectronic apparatus has been exposed to the theft, regardless of thejudgment identification code inputted by the identification code inputmeans.
 12. The method of cancelling the inoperable state of theelectronic apparatus having the security function of claim 10, whereinthe output code is calculated using the individual code stored in thenonvolatile individual code memory.
 13. A method of cancelling aninoperable state of an electronic apparatus, wherein the electronicapparatus includes a security function that has determined that theelectronic apparatus has been exposed to theft, and wherein said methodcomprises comprising: judging whether the electronic apparatus has beenexposed to the theft; putting the electronic apparatus into aninoperable state against the theft in which a predetermined operation ofa controlled circuit is disabled, the electronic apparatus being putinto the inoperable state when said judging of whether the electronicapparatus has been exposed to the theft judges that the electronicapparatus has been exposed to the theft; storing an individual codeindividually assigned to the electronic apparatus; outputting an outputcode having a predetermined first relationship with the individual code,the output code being calculated in the electronic apparatus using theindividual code stored in said storing of the individual code; inputtingan individual judgment code; judging whether the individual judgmentcode inputted in said inputting of the individual judgment code and acode calculated based on the individual code have a predetermined secondrelationship; cancelling the inoperable state against the theft in whichthe predetermined operation of the controlled circuit is disabled, theinoperable state being cancelled when said judging of whether theinputted individual judgment code and the code calculated based on theindividual code have the predetermined second relationship judges thatthe individual judgment code and the code calculated based on theindividual code have the predetermined second relationship, theindividual judgment code and the code calculated based on the individualcode having the predetermined second relationship when the output codeand the individual judgment code have a predetermined thirdrelationship; deriving, in a dealer-use calculation device external tothe electronic apparatus, the individual judgment code having thepredetermined third relationship with the output code, the individualjudgment code being derived from the output code output in saidoutputting of the output code; supplying the output code output in saidoutputting of the output code to the dealer-use calculation device; andinputting the individual judgment code derived in said deriving of theindividual judgment code and having the predetermined third relationshipwith the output code to the electronic apparatus.
 14. The method ofcancelling the inoperable state of the electronic apparatus having thesecurity function of claim 13, further comprising: storing anidentification code of the controlled circuit; inputting a judgmentidentification code of the controlled circuit; and judging, in theelectronic apparatus, whether the identification code stored in saidstoring of the identification code and the judgment identification codeinputted in said inputting of the judgment identification code have apredetermined judgment identification relationship, wherein: when saidjudging of whether the stored identification code and the inputtedjudgment identification code have the predetermined relationship judgesthat the stored identification code and the inputted judgmentidentification code have the predetermined judgment identificationrelationship, the predetermined operation of the controlled circuit isenabled; when said judging of whether the stored identification code andthe inputted judgment identification code have the predeterminedrelationship judges that the stored identification code and the inputtedjudgment identification code do not have the predetermined judgmentidentification relationship, the electronic apparatus is put into aninoperable state for confirmation in which the predetermined operationof the controlled circuit is disabled; when a predetermined conditionrelating to said inputting of the judgment identification code isestablished, said judging of whether the electronic apparatus has beenexposed to the theft judges that the electronic apparatus has beenexposed to the theft; and said putting of the electronic apparatus intothe inoperable state against the theft does not enable the predeterminedoperation of the controlled circuit after said judging of whether theelectronic apparatus has been exposed to the theft judges that theelectronic apparatus has been exposed to the theft, regardless of thejudgment identification code inputted in said inputting of the judgmentidentification code.